Assessment of Occupational Exposure of Forest Firefighters to Woodsmoke Using Levoglucosan, Particulate Matter and Carbon Monoxide

The exposure of wildland firefighters at prescribed burns and wildfires have typically being assessed using particulate matter and carbon monoxide (CO). Levoglucosan (LG), a major organic constituent of particles in woodsmoke, was measured and used together with particulate matter with median aerodynamic diameter of 2.5 microns (PM2.5) and CO to assess the exposures of eighteen wildland firefighters at 30 prescribed burns (n=157 person-days) at the Savannah River Site (SRS), SC. The effects of various factors on the exposure of the firefighters were investigated using linear mixed effects models. Exposures to PM2.5 (64-2068 µg/m3) and CO (0.02-8.2 ppm) averaged over the work-shift duration fell within the ranges observed in previous studies. Some recommended shorter term exposure limits for CO were exceeded in a few instances. The LG:PM2.5 ratio averaged 6.9% (95% CLs: 5.4, 8.5%) with nine samples having a ratio below 1%. Exposure to PM2.5 and CO were higher when firefighters performed “holding” tasks compared with “lighting” duties, while exposures to CO and LG were higher when burns were in compartments with predominantly pine vegetation (p<0.05). The very low LG:PM2.5 ratios in some samples suggest that the exposures of wildland firefighters to pollutants at prescribed burns may be substantially impacted by non-woodsmoke sources.